[1] Department of Criticality and Fuel Cycle Research Facilities, Japan Atomic Energy Agency, 2-4 Shirane, Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
[2] Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, 2-4 Shirane, Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
[3] Naka Energy Research Laboratory, Energy Project and Technology Center, Mitsubishi Materials Corporation, 1002-14, Mukoyama, Naka-shi, Ibaraki 311-0102, Japan
[4] Cabinet Office, Goverment of Japan
[5] Japan Science and Technology Agency